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net: check packet payload length

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While computing IP checksum, 'net_checksum_calculate' reads
payload length from the packet. It could exceed the given 'data'
buffer size. Add a check to avoid it.

Reported-by: Liu Ling <liuling-it@360.cn>
Signed-off-by: Prasad J Pandit <pjp@fedoraproject.org>
Signed-off-by: Jason Wang <jasowang@redhat.com>
This commit is contained in:
Prasad J Pandit 2016-03-02 17:29:58 +05:30 committed by Jason Wang
parent f1b2bc601a
commit 362786f14a
1 changed files with 8 additions and 2 deletions
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10
net/checksum.c
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@ -60,6 +60,11 @@ void net_checksum_calculate(uint8_t *data, int length)
int hlen, plen, proto, csum_offset; int hlen, plen, proto, csum_offset;
uint16_t csum; uint16_t csum;
/* Ensure data has complete L2 & L3 headers. */
if (length < 14 + 20) {
return;
}
if ((data[14] & 0xf0) != 0x40) if ((data[14] & 0xf0) != 0x40)
return; /* not IPv4 */ return; /* not IPv4 */
hlen = (data[14] & 0x0f) * 4; hlen = (data[14] & 0x0f) * 4;
@ -77,8 +82,9 @@ void net_checksum_calculate(uint8_t *data, int length)
return; return;
} }
if (plen < csum_offset+2) if (plen < csum_offset + 2 || 14 + hlen + plen > length) {
return; return;
}
data[14+hlen+csum_offset] = 0; data[14+hlen+csum_offset] = 0;
data[14+hlen+csum_offset+1] = 0; data[14+hlen+csum_offset+1] = 0;